Overheated lexus gs300

I had a timing belt changed at 180,000 miles on a 2001 GS300 by a Lexus dealer service. Two weeks later at 70 mph (well 65 if the Troopers are reading this) on the NY Thruway steam erupted from the engine compartment. I immediately pulled off to the side of the road, and at the same time noticed that the temp gauge was reading at its maximum (HOT). Turned off the engine, and towed the car to the Lexus dealer where it sits waiting for them to look at it for damage. The reason for the overheating? The mechanic, aka Lexus Service Engineer, forgot to replace the water hose clamp at the top of the radiator when the timing belt job was completed. Obviously, the expense (towing, repair, etc. will be on the dealer!!

The questions are, is it possible there was damage to the engine, the head (aluminum?), the transmission, etc.? Should I ask for anything more than a compression test? What should I look/listen for that might indicate damage if they tell me all is well?

If you IMMEDIATELY took the car off the road when the temperature gage shot up, there will probably be no damage. This thing happened to me when a rad hose burst (my fault for not inspecting it more frequently) on an urban freeway, and I drove another mile to the nearest exit where a dealer was located. The inspection revealed no damage, and after new coolant and a rad hose, I was on my way. This car had a cast iron block and heads.

I would recommend an inspection since the dealeship screwed up. You did the right thing by stopping IMMEDIATELY!